1. Field of the Invention
The present invention relates to polyols containing a separate polymer. They are usually referred to in the art as polymer polyols.
2. Description of the Prior Art
Polyurethanes constitute a broad class of polymeric materials having a wide range of physical characteristics. The polymers are produced through the interaction of a polyfunctional isocyanate with a polyfunctional chemical compound having an active hydrogen in its structure, such as a polyester or polyether or mixtures of two or more of such materials. The materials conventionally used contain two or more hydroxyl groups and are thus generally termed polyols.
It is known in the art that the addition of a high molecular weight polymer to polyurethane compositions will improve certain of the physical properties of the resulting polyurethane composition. There have been many efforts with respect to incorporating polymers into such polyurethane compositions. For example, U.S. Pat. No. 3,383,351 discloses the in situ polymerization of an ethylenically unsaturated monomer in the presence of the polyol component of a polyurethane composition. Prior art techniques include the method of polymerizing ethylenically unsaturated monomers in the presence of isocyanate terminated prepolymers to result in an isocyanate terminated polymer prepolymer. A description of this technique may be found in U.S. Pat. No. 3,968,089. Also, preparation of graft co-polymer dispersions by in situ polymerization of a vinyl monomer in an unsaturated containing polyol is described, for example, in U.S. Pat. No. 3,953,393.
We have discovered a method whereby a polymer may be formed so as to achieve a degree of freedom not found in the prior art techniques.